1. Field of the Invention
The present invention provides apparatus for moving a microplate to accommodate higher density microplates when fluid is being dispensed from a conventional 96 head pipette dispenser.
2. Description of the Prior Act
U.S. Pat. No. 5,497,670 issued Mar. 12, 1996, the subject matter set forth therein invented by the inventor of the present invention, discloses an improved dispensing head apparatus including means for loading pipette tips carried by a pipette plate onto liquid dispensing cylinders, the loading force being maintained during the apparatus operation cycle, thus ensuring a proper seal between the pipette tip and the cylinder. The pipette tips are manually placed on the tip plate, the plate sliding within the dispensing apparatus.
Although the pipette tip plate holder described in the aforementioned patent provides many advantages when used with the apparatus described therein, there are certain disadvantages associated with it use. In particular, there is a possibility that the pipette tip plate holder may become contaminated. More importantly, the pipette tip plate configuration is not easily adapted for robotics operation or automation.
U.S. patent application Ser. No. 08/751,859 filed Nov. 18, 1996 the subject matter set forth therein also invented by the inventor of the present invention, provides a self contained fluid head dispensing apparatus similar to that disclosed in the aforementioned patent but modified to the extent that the pipette tip plate disclosed therein is replaced with a more conventional pipette tip box which is less expensive, is less likely to be contaminated and wherein the carrier is easily adapted for robotics operation or automation.
A microplate containing 96 wells with 9 mm on centers spacing in a 8 by 12 array is typically used with most dispense apparatus. The early prior act dispense devices started with one fluid dispenser and moved in the x-y direction 96 times to dispense into each of the 96 wells. Over time, dispense devices were added to include one row (8 or 12 wells per row) and then indexing either 8 or 12 times to fill the entire plate. A 96 dispense apparatus device to fill an entire plate at one time is disclosed, for example, in the '670 patent noted above.
The microplate has recently changed in design. Higher production speeds and larger storage libraries require higher density formats. The 96 well format with its 9 mm spacing has increased to 384 wells with 4.5 mm spacing. The 384 microplate has increased to 864 and now 1536 with 2.25 mm spacing between well centers. These different density plates have the same foot print (length, width).
A 96 head pipette dispenser can be used for either 96 well plates or higher 384 or 1536 density well plates. Therefore, there is a need to either move the dispense head or the plate for the higher density plates. Since it is easier to move the microplate rather than move the relatively heavy dispense head, it is an obvious choice to design a system to move the microplate. The 96 head pipette dispenser can work with a 384 well microplate if the head or microplate is moved 4 times and dispensed 4 times (FIG. 7 to FIG. 8). Therefore a 96 pipette dispense head can move fluid from one 384 plate to another 384 plate, the wells being designated as quadrant in a four well configuration. This is accomplished in a quadrant to quadrant move (one well being designated as a quadrant). In the first move, fluid from a first well of the first plate is moved to the first well of the second plate. Therefore, there are 4 moves required for a 384 to 384 transfer.
There is frequently a need to preform a conversion from 96 to 384 well formatted plates (compression) or 384 to 96 well formatted plates (expansion). If 96 to 384 conversion is needed, it will require 5 motions, one aspirate and four dispenses. Thus what is desired is to provide a 5 position motion device which enables fluid to be accurately transferred between 384 and 96 well formatted plates and other well formatted plates (i.e. from a 384 well formatted plate to a 1536 well formatted plate).